Multi-station RF thermometer and alarm system

ABSTRACT

A multi-station RF thermometer and alarm system measures temperatures and/or percent relative humidity at remote locations by RF weather stations, and displays received temperature and/or other weather data telemetry on a multi-station base station that provides out-of-bounds alarm signal indications whenever temperatures are outside of user-selectable minimum and maximum values. Randomized transmission times in one embodiment and two-phase unique transmission schedules in another lessen the possibility of on-going collisions between two or more transmitters contending for the base station at the same time. Redundant data transmission lessens the possibility of environmental noise interference. The redundant data, transmitted at random times in one embodiment, includes a unique channel ID code, house-keeping data, the current temperature and/or time-to-next-transmission data, and in another embodiment, transmitted at uniquely prescheduled times of two-phase transmission schedules, includes station location ID and transmission schedule phase. The weather parameter sensing transmitters operate at a low duty cycle with low peak current consumption resulting in long battery life. The multi-station base station may be AC- or battery-powered. Channel and station ID switches are provided on the remote temperature sensing transmitters and on the multi-station base station in one embodiment and a station ID number selection switch is provided in another transmitter embodiment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This invention is a division of allowed continuation-in-part applicationSer. No. 09/421,974 filed Oct. 20, 1999 now U.S. Pat. No. 6,300,871,which is a continuation of U.S. utility patent application Ser. No.08/968,290 filed Nov. 12, 1997, now U.S. Pat. No. 6,046,674, eachincorporated herein by reference.

FIELD OF THE INVENTION

This invention is drawn to the field of telemetry, and moreparticularly, to a novel multi-station RF thermometer and alarm system.

BACKGROUND OF THE INVENTION

Many of life's activities are heavily influenced by the temperature.Heretofore, hard-wired digital thermometers, such as the model IOTA1 andthe model IOTA2 commercially available from TREND Industries, Inc., orthe Electronic Weather Station With Alarm Clock, commercially availablefrom CATHAY PACIFIC, measure temperature by a hard-wired probe, anddisplay the measured temperature on an associated display. Suchhard-wired digital thermometers, however, need to be placed withininches or feet of the environment to be measured. This can beinconvenient, as this type of digital thermometer is not placed where itis most accessible and likely to be needed (e.g., next to a bed, on adesk, etc.), but where it must be placed to work.

Wireless (RF) digital thermometers, such as the model “7055” WirelessWeather Station With Radio Controlled Clock, commercially available fromEurope Supplies, Ltd., measure temperature by a remote wirelesstemperature station and display the measured temperature on a displayassociated with a base station. Although in principle such transmittersmay be remotely located to the base, environmental noise sources havegenerally limited their practical range and have given rise to erroneoustelemetry and lack of operator confidence. And if more than one locationneeds to be monitored, another such RF transmitter and base pair needsto be provided for every location to be measured. Not only has thisresulted in increased overall costs, and undesirable multiplication ofbase stations, but the utility of such transmitter/base pairs hasfurther been limited by contention-induced interference as transmissionsfrom the multiple transmitters collide at each base station.

Moreover, both the hard-wired and RF temperature thermometers heretoforehave had their utility limited by probe placement difficulties, wheneverlocations that are other than directly exposed and in the open are to bemonitored, and by a general inability to provide information of comfortlevel or of weather situations that may endanger well-being.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to disclose amulti-station RF thermometer and alarm system suitable for home, officeand light industrial use.

It is another object of the present invention to disclose amulti-station RF thermometer and alarm system that provides temperaturemonitoring of plural remote locations and at a local base station.

It is another object of the present invention to disclose amulti-station RF thermometer and alarm station that provides reliabletemperature or other weather parameter, such as humidity, transmissionand reception in the presence of interference (environmental noiseinterference and contention-induced interference).

It is another object of the present invention to disclose amulti-station RF thermometer and alarm system that provides user-setablealarm limits for each of multiple remote and/or local locations and thatprovides alarm signals whenever out-of-bounds conditions prevail at anylocation.

It is another object of the present invention to disclose amulti-station RF thermometer and alarm system that provides accuratetemperature or other weather parameter, such as humidity, sensing andtransmission over wide temperature, humidity and distance ranges in amanner that requires low power consumption suitable for long-lifebattery operation.

It is another object of the present invention to disclose amulti-station RF thermometer and alarm system that responds totemperature and humidity telemetry and provides heat index informationnot only useful as a general comfort indicator, but may also proveinvaluable in times when high temperature and high humidity can lead todangerous heat stroke levels.

In accord therewith, the disclosed multi-station RF thermometer andalarm system of the present invention includes at least one portable,battery-powered temperature station and a multi-station base station.Each of the at least one portable, battery-powered temperature stationsprovides, as desired, measurement of temperatures in rooms,refrigeration devices, pools, outdoor areas, etc., and the multi-stationbase station, which may be placed on a desk, at bedside, or otherwise asconvenient, receives and displays, preferably concurrently, the measuredtemperature data received from the one or more portable, battery-poweredtemperature stations and measured at the multi-station base station.

In one preferred embodiment, each temperature station transmits remotetemperature measurements over a two-hundred and fifty foot (250′) rangeto the multi-station base station and is operable over an activeindoor/outdoor temperature range from minus forty degrees (−40)° F. toone hundred and fifty eight (158)° F. In this embodiment, themulti-station base station receives and displays temperature from up tofour (4) remote transmitters.

Accordingly to one aspect of the present invention, the portable,battery-powered temperature station includes an analog temperaturesensor providing a temperature signal representative of sensedtemperature; an antenna; and a processor-controlled transmitter coupledto the antenna and to the temperature signal operative (1) toperiodically convert the temperature signal to a digital representationof the sensed temperature, (2) to digitally encode a data frame havingfirst information representative of the sensed temperature and secondinformation representative of station ID, and (3) to transmit apredetermined integral number greater than one (1) of data frames eachhaving said first and said second information at a random time. Therandomized transmission times, and redundantly encoded temperature andtransmitter ID data, cooperate to alleviate collision-induced contentionand to provide reliable data transmission in noisy environments. In thisembodiment, the temperature data is read every thirty (30) seconds andfive (5) redundant data frames are randomly transmitted once everythirty (30) to sixty (60) seconds.

Accordingly to a further aspect of the present invention, the portable,battery-powered temperature station includes an analog temperaturesensor providing a temperature signal representative of sensedtemperature; an antenna; and a processor-controlled transmitter coupledto the antenna and to the temperature signal operative (1) toperiodically convert the temperature signal to a digital representationof the sensed temperature, (2) to generate a schedule of present andfuture random transmission times, (3) to digitally encode a data framehaving first information representative of the sensed temperature,second information representative of station ID, and third informationrepresentative of the schedule of present and future random transmissiontimes and (4) to transmit a predetermined integral number of data frameseach having said first, said second and said third information at arandom time. The schedule of present and future random transmissiontimes allows the multi-station base station to “sleep” at times when notransmissions are scheduled, or when previous transmissions indicatevery little temperature change, thereby conserving power enablinglong-life battery-powered base station operation.

According to another aspect of the present invention, the disclosedportable, battery-powered temperature station includes a housing; awaterproof probe electrically connected to the housing via an elongatedflexible cable of predetermined length; an attachment member for stowingthe probe to the housing when not in use; and means for paying out anyselected length of the elongated flexible cable of predetermined lengthselected to accommodate the needs of each particular application. In onepreferred embodiment, the housing includes a front wall and a batteryreceiving compartment, and the attachment member includes a well formedin the front wall of the housing dimensioned to frictionally receive theprobe, and the pay-out means includes a wire-receiving chamber providedin the battery compartment of the housing. The selectably extendableprobe enables to measure hard-to-reach areas, such as the watertemperature of an outdoor pool or the inside temperature of a storagefreezer.

According to another aspect of the present invention, the disclosedmulti-station base station includes a multi-field reconfigurabledisplay; operator input means; a receiver for providing an output signalin response to transmissions received from each at least one portable,battery-powered temperature station; and a processor coupled to thedisplay, to the input means, and to the receiver, that is operative in adecode/display mode, an alarm set mode, and an alarm announce mode.

In the decode/display mode, the processor is operative (1) to configurethe display with a field that corresponds to each of multipletemperature station zones, (2) to recover from the output signal of thereceiver the first information representative of sensed temperature andthe second information representative of the transmitting station ID foreach data frame of the redundantly transmitted data frames, and (3) todisplay the recovered temperature data in a field corresponding to anidentified station if the first information representative of the sensedtemperature of two (2) of the redundantly transmitted data framesconform to each other for a given station.

In one preferred embodiment, the display is configured with acomparatively-large “active” location field, with five (5) temperaturestation fields (four (4) remote station and one (1) base stationfields), and with temperature high and low fields, and the processor isoperative in the decode/display mode to display the current temperatureof any temperature station in the comparatively large “active” locationfield and the daily high and low temperatures in the corresponding highand low temperature fields in response to operator input stationselection, and to concurrently display the temperature at any activelocations (remote and/or base) in the corresponding ones of the five (5)temperature station fields. Other display configurations, such asconcurrent and/or sequential display of less than all of the activelocations, and operator input station display selection, could beemployed.

In the alarm set mode, the processor is operative to configure thedisplay with alarm min and alarm max fields and with at least one alarmset station field, and is operative in response to operator inputstation (base or remote) selection, in response to operator input alarmmin and max values selection and in response to operator input alarmarming to set and to display min and max temperature bounds for eachstation selected and armed. Min/max setpoints for temperature range maybe set for all locations. If the temperature in any location goesoutside this set range, an alarm (visible, audible and/or remote) signalindication is provided in alarm announce mode. In the preferredembodiments, all stations that have been armed are concurrentlydisplayed, although sequential display in response to operator inputstation display selection could be employed.

In alarm announce mode, the processor is operative to configure thedisplay with an alarm announce icon field and at least one active alarmstation field, and is operative (1) to display a location where anactive alarm condition exists in the active alarm station field, (2) toprovide an alarm signal indication, and (3) is operative in response tooperator alarm dis-arm input to clear the alarm condition for each alarmlocation. The alarm signal may be an audible, a visible, and/or a remotealarm signal. In the preferred embodiments, all stations that haveactive alarm conditions are concurrently displayed, although sequentialdisplay in response to operator input station display selection could beemployed.

In one embodiment, the multi-station base station is AC outlet powered,and in other embodiments, it is battery-powered.

In further disclosed embodiments, each portable, battery-powered weatherstation is operative to alternatively transmit percent relative humidityand temperature data redundantly in accord with a schedule oftransmission times unique to each portable, battery-powered weatherstation. The redundant transmission of weather data helps prevent noiseinterference at the multi-station base station, and the unique schedulesof transmission times both held prevent contention-induced interferenceat the multi-station base station as well as allow the multi-stationbase station to enter battery-power-conserving mode when no receptionsare scheduled from each of the portable weather stations.

For each of the portable, battery-powered weather stations that measureand transmit temperature and percent relative humidity data, themulti-station base station selectably calculates and displays heat indexinformation.

A method of encoding data at the portable, battery-powered weatherstations to maximize transmission range and detection sensitivity at thebattery-powered multi-station base station is disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, inventive aspects, and advantageous featureswill become apparent as the invention becomes better understood byreferring to the following detailed description of the presentlypreferred embodiments, and to the drawings, wherein:

FIG. 1 is a functional block diagram of the multi-station RF thermometerand alarm system of the present invention;

FIG. 2 is an elevational view of the front of one embodiment of theportable, battery-powered temperature station of the present invention;

FIG. 3 is a perspective view of the back of the portable,battery-powered temperature station of the present invention with thebattery door and wall mounting bracket removed;

FIG. 4 is a functional block diagram of the portable, battery-poweredtemperature station of the multi-station RF thermometer and alarm systemof the present invention;

FIG. 5 is a diagram illustrating the data format of the portable,battery-powered temperature station of the present invention;

FIG. 6 is a schematic circuit diagram of the RF oscillator of theportable, battery-powered temperature station of FIG. 4;

FIG. 7 is a flow chart of the processor of the portable, battery-poweredtemperature station of FIG. 4;

FIG. 8 is a front elevational view of one embodiment of themulti-station base station of the multi-station RF thermometer and alarmsystem of the present invention;

FIG. 9 is a functional block diagram of the multi-station base stationof the present invention;

FIG. 10 is a schematic circuit diagram of the receiver of themulti-station base station of FIG. 9;

FIG. 11 is a state diagram of the processor of the multi-station basestation of FIG. 9;

FIGS. 12-14 are pictorial diagrams illustrating the multi-fieldreconfigurable display of the multi-station base station of FIG. 9respectively configured in decode/display mode, alarm set mode and alarmannounce mode;

FIG. 15 is a flow chart of the processor of the multi-station basestation of FIG. 9;

FIG. 16 is an elevational view of the front of another embodiment of aportable, battery-powered weather station of the present invention;

FIG. 17 is a functional block diagram of the portable, battery-poweredweather station of the multi-station RF thermometer and alarm system ofthe present invention;

FIG. 18 is a diagram illustrating the data format of the portable,battery-powered weather station of the present invention;

FIG. 19 is a flow chart of the processor of the portable,battery-powered weather station of FIG. 17;

FIG. 20 illustrates in the FIGS. 20A-20C thereof front elevational viewsof another embodiment of a battery-powered multi-station base station ofthe multi-station RF thermometer and alarm system of the presentinvention for use with the portable, battery-powered weather station ofFIGS. 16-19;

FIG. 21 is a functional block diagram of the multi-station base stationof the present invention;

FIG. 22 is a state diagram of the processor of the multi-station basestation of FIG. 21; and

FIG. 23 is a flow chart of the processor of the multi-station basestation of FIG. 21.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Referring now to FIG. 1, generally designated at 10 is a functionalblock diagram of the multi-station RF thermometer and alarm system inaccord with the present invention. The system 10 includes a plurality ofRF thermometers or other weather stations 12 to be described and amultichannel base station 14 in spaced apart relation to the plural RFthermometers 12. The system 10 is adapted for home, office and lightindustrial use. The RF thermometers 12 are portable, battery-powereddevices that may be placed anywhere where temperatures are to bemonitored. For example, one temperature transmitter 12 could be attachedto the back of the house, another in the pool, a third in a green house,and a fourth in the garden, not shown.

The multi-channel base station 14 includes a receiver, not shown, to bedescribed that receives the temperatures or other weather datatransmitted by the plural RF thermometers 12 and displays temperaturedata received from the plural RF thermometers 12 on display 16. Themultichannel base station 14 also displays the temperature at the basestation by means of the display 16. In the presently preferredembodiments, the display 16 displays the temperature at the base station14, as well as the temperatures at each of the remote RF thermometers12, concurrently. Other temperature display methodologies, such assequential display of the temperatures at plural remote and base stationlocations may be employed.

The multichannel base station 14 monitors the temperature data receivedfrom each of the plural remote RF thermometers 12 and the base station14 and compares the received temperatures and the base stationtemperature to user-setable alarm limits to be described for each remotelocation and the base station. In the preferred embodiments, the alarmlimits are minimum and maximum limits independently user setable foreach location (base and remote). If the received temperatures and thelocal base station temperature are out of the bounds set by the alarmlimits for any location, the multichannel base station 14 provides analarm as schematically illustrated by box 18. The alarm 18 in thepreferred embodiment includes an audible and a visible alarm signal.

A remote dialer 20 is connected to the multichannel base station 14. Theremote dialer 20 is connected to a remote station 22 via the phonenetwork 24. The remote dialer 20 sends all temperature data to theremote display 22 at preset times, or when alarm conditions exist at anylocation.

The remote station 22 receives and displays all temperature or otherdata sent by the remote dialer 22. The remote station 22 may dial theremote dialer 20 via the phone network 24 to request the currenttemperature data for any location, as well as the corresponding alarmlimits.

The remote station 22 preferably includes a DTMF generator and a DTMFlistener, not shown, that cooperate to send control information via thephone lines, and to receive data back from the multi-station basestation in accord with the control information sent. The remote userinto this way may, for example, request the current temperatureinformation from all stations (remote and base) from the multi-stationbase station.

To manage interference (contention-based interference arising from theplural RF thermometers competing with the multichannel base station aswell as noise interference arising in the intended operatingenvironment), the multi-station RF thermometer and alarm system 10 ofthe present invention employs four (4) principal measures. First, eachRF thermometer 12 and the multichannel base station 14 in one embodimentare provided with dual, user selectable channels “A” and “B” to bedescribed. For example, interference from another multi-station RFthermometer and alarm system operating in the same locale may beeliminated by switching from one to the other of the two (2) channels.Second, each RF thermometer 12 in one embodiment transmits itstemperature data at random times, preferably once every thirty (30) tosixty (60) seconds. The randomness of the transmissions makes itstatistically unlikely that temperature data from multiple RFthermometers arrive simultaneously at the multichannel base station 14.In another embodiment, each RF weather station 12 transmits itstemperature and/or humidity data in accord with a schedule oftransmission times unique to each weather station. Third, each RFthermometer 12 transmits redundant temperature and station IDinformation. In one embodiment, five (5) redundant data framesconstitute the data telemetry. Should environmental noise sourcescorrupt part of the telemetry, the multichannel base station 14 would beable to recover any uncorrupted part thereof. Fourth, the multichannelbase station 14 maintains a record of time of receipt for each RFthermometer 12 data transmission and updates temperature data receivedfrom the plural RF thermometers 12 provided the same is received withina predetermined time window. So long as the temperature data from eachchannel (station) is received within the predetermined time window,preferably fifteen (15) minutes in one embodiment and one (1) hour inanother embodiment, from the time of last receipt, the multichannel basestation updates the temperature information it maintains for eachchannel. Otherwise, it provides an indication of an inoperable channel.These channel recovery windows should be sufficient for most noisyenvironments, although a different duration window could be employed.

Referring now to FIG. 2, generally designated at 40 is an elevationalview of the front of one embodiment of the RF thermometer of themulti-station RF thermometer and alarm system of the present invention.The RF thermometer 40 includes a water-resistant housing 42 havingO-ring seals, not shown, a well generally designated 44 integrallyformed in the housing 42 for receiving a temperature probe, and awaterproof temperature probe 46 shown received in the probe receivingwell 44. The waterproof probe 46 is connected to the housing 42 via anelongated flexible cable 48 of predetermined length, preferably ninety(90) centimeters. A display 50 for displaying the temperature sensed bythe probe 46 is mounted to the housing 42. The RF thermometer 40 isbattery-powered, is operational from minus fifty (−50) to plus seventy(+70) Co, has a range of sixty (60) meters obstructed (i.e. throughwalls), an accuracy of +/− 0.5 Co and a minus forty (−40) to a plusforty (+40)Co range for reliable temperature measurement.

Referring now to FIG. 3, generally designated at 60 is a perspectiveview of the back of the portable, battery-powered RF transmitter of themulti-station RF thermometer and alarm system of the present inventionwith its battery door and wall mounting bracket removed. Chambergenerally designated 62 defined in the battery receiving compartmentprovides a space in which the cable 48 may be looped and stored betweenbatteries 64. Any selected length of the cable 48 of predeterminedlength may be payed-out of the chamber 42 to allow the waterproof probe46 to reach intended temperature measurement locations as determined bythe needs of each particular applications environment.

As shown, channel “A” and “B” selector and station ID switches 66, 68are preferably mounted in the battery compartment, although any othersuitable location therefor could be employed.

Referring now to FIG. 4, generally designated at 70 is a functionalblock diagram of the portable, battery-powered RF thermometer of themulti-station RF thermometer and alarm system of the present invention.Digital controller 72, operatively connected to RAM memory and ROMmemory, not shown, is connected to channel setting and stationidentifying DIP switches 74, temperature sensor 76, LCD display 78, anda three hundred and fifteen (315) megahertz RF oscillator 80. Thechannel set switches 74 preferably are two (2) DIP switches (containingfour (4) SPST switches each), each for channel “A” and for channel “B”.In use, each RF thermometer is set to a different four (4) bit ID codeon either channel, and the receiver is set to either bank A or bank B.This minimizes the problem of interference from a neighboringmulti-station RF thermometer and alarm system, and/or from environmentalsources of interference. Although channel selecting and stationidentifying DIP switches are presently preferred, other channel settingand/or station identifying means in the transmitter could be employed.

The controller 72 preferably is a OKI Semiconductor MSM64162microcontroller (with internal RAM and ROM). The temperature sensor 76preferably is a Semitec 103AT-2B thermistor. The LCD display 78preferably is a custom-manufactured display.

The controller 72 (1) measures the resistance of the thermistor of thetemperature sensor 76 and numerically calculates the temperaturecorresponding thereto, (2) encodes a data packet having redundant firstdata representative of the sensed temperature and redundant second datarepresentative of the transmitter ID and (3) controls the RF oscillator80 to transmit a data frame having the encoded data packets at randomtime. In addition, the controller 72 performs the functions ofdisplaying the temperature on the liquid crystal display 78 and checkingthe battery voltage.

In one preferred embodiment, the controller 72 transmits eight hundredeighty five (885) millisecond data packets on a randomized schedule ofapproximately twice per minute, randomly selected every thirty (30) tosixty (60) seconds, with no less than thirty seconds betweentransmissions. The average duty cycle of any one hundred (100)millisecond portion of the transmission does not exceed fifty (50)percent, permitting a six (6) dB increase in the peak output power fromthe transmitter. The eight hundred and eighty five (885) millisecondtransmission consists of a preamble followed by five (5) identical dataframes as shown in FIG. 5. A Manchester-like encoding technique ispreferably used for the data frames.

A preamble signals the start of transmission and allows the data slicertime to stabilize before the data is sent. Each data frame contains await (low) pulse, a sync (high) pulse, a start (low) pulse, a sixteen(16) bit channel ID word, a four (4) bit setup word and a sixteen (16)bit BCD temperature word.

The preamble is a square-wave train, consisting of twenty (20) highpulses and nineteen (19) low pulses. The wait pulse is low for two (2)bit periods. The sync pulse is high for four (4) bit periods. The startpulse is low for two (2) bit periods. The data is sent as (bit) followedby (complement of bit). Thus, the sixteen (16) bit ID word isrepresented by thirty two (32) bits, the four (4) bit setup word isrepresented by eight (8) bits, and the sixteen (16) bit temperature wordis represented by thirty two (32) bits. The complete transmission isfour hundred and thirty nine (439) bit periods in duration.

Example of Complete Transmission:

-   Channel ID=1101 0011 0101 100=D358-   Temperature=024.7-   (preferably transmitted in ° F.)=000 0010 0100 0111=0247-   Setup Word=(positive temperature, unused bit, unused bit, battery    good)=1010-   The bits are converted so 0's are represented by 01 and 1's are    represented by 10. Using this, the data becomes:

Channel ID = 1010 0110 0101 1010 0110 0110 1001 0101 Setup Word = 10011001 Temperature = 0101 0101 0101 1001 0110 0101 0110 1010 ActualTransmission: 1010 1010 1010 1010 1010 1010 1010 1010 1010 101 preamble00 wait FRAME 1 1111 sync 00 start 1010 0110 0101 1010 0110 0110 10010101 channel ID 1001 1001 setup data 0101 0101 0101 1001 0110 0101 01101010 temperature 00 wait FRAME 2 1111 sync 00 start 1010 0110 0101 10100110 0110 1001 0101 channel ID 1001 1001 setup data 0101 0101 0101 10010110 0101 0110 1010 temperature 00 wait FRAME 3 1111 sync 00 start 10100110 0101 1010 0110 0110 1001 0101 channel ID 1001 1001 setup data 01010101 0101 1001 0110 0101 0110 1010 temperature 00 wait FRAME 4 1111 sync00 start 1010 0110 0101 1010 0110 0110 1001 0101 channel ID 1001 1001setup data 0101 0101 0101 1001 0110 0101 0110 1010 temperature 00 waitFRAME 5 1111 sync 00 start 1010 0110 0101 1010 0110 0110 1001 0101channel ID 1001 1001 setup data 0101 0101 0101 1001 0110 0101 0110 1010temperatureThe entire transmission consists of four hundred thirty nine (439) bitsin eight hundred eighty five (885) milliseconds, with a bit duration of2.016 milliseconds.

In another preferred embodiment, where time-of-next transmissionscheduling is included in the data frames as a means of conserving powerin the multi-station base station, the data frames, in addition to thepreamble, channel ID, and temperature words, include time-to-nexttransmission information. If the “time to next transmission” isrepresented in seconds, six (6) bits will give zero (0) to sixty-three(63) seconds of wait time. Inclusion of these bits (and the complementedbits) adds an additional twelve (12) bits to each frame and sixty (60)bits to the complete packet, giving a four hundred ninety nine (499) bittransmission. An alternative means of specifying the “time to nexttransmission” is to send the number of seconds deviation from theaverage transmission interval. For instance, if the transmissionrandomly deviates by plus/minus ten (10) seconds from a nominal value offorty (40) seconds, a five (5) bit time code could be used (range 00-31seconds or plus/minus 16 seconds). If it is desired to have a muchlonger interval between transmissions, the actual time and date of thenext transmission(s) could be set. This could be represented in BCDdigits in seconds/hr/days/month format, or by a count-down timeexpressed in seconds (or tens of seconds, or hundreds of seconds, and soon.) Other schemes may be employed as well without departing from theinventive concepts.

Referring now to FIG. 6, generally designated at 100 is a schematiccircuit diagram of the RF oscillator of the portable, battery-powered RFtransmitter of FIG. 4. The RF oscillator includes transistor Q1 in asaturated Pierce-like oscillator configuration, preferably resonant atthree hundred and fifteen (315) megahertz, with frequency stabilized bySAW resonator marked “SAW1” connected to the base of transistor Q1. Aloop antenna marked “LOOP ANT” is preferably etched with the oscillatoron a printed circuit board, not shown. ON/OFF keying (“OOK”) modulationof the three hundred and fifteen (315) megahertz carrier is provided forby applying zero (0) and positive three (+3) volt logic levels to thedata input (resistor R3) from the controller 72 (FIG. 4). Elements R1,R2, R3, R4 and R5 set the operating point of transistor Q1; (R3 alsoserves as an input port for modulating the transmitter), elements C4, C5and C6 in conjunction with the loop antenna provide a tuned outputnetwork that attenuates harmonics. C3 is a bypass capacitor to preventRF energy being fed back to the controller through the data input .Element C1 is a bypass capacitor to provide a low impedance path for thecirculation of RF current. C2 couples the output network to thecollector of Q1. L1 is the collector inductor.

Referring now to FIG. 7, generally designated at 110 is a flow chartillustrating the operation of the controller of the portable,battery-powered RF thermometer of the multi-station RF thermometer andalarm system of the present invention.

As shown by a block 112, the processor is operative to initialize, andas shown by a block 114, is operative to determine whether five (5)seconds have elapsed.

If five (5) seconds have elapsed, the processor is operative to checkchannel identification and battery status as shown by a block 116.Although the processor preferably checks channel ID and battery statusevery five (5) seconds, other intervals could be employed.

As shown by a block 118, the processor is then operative to determinewhether it is time to randomly transmit its data packet of redundantdata frames. Any suitable technique, such as a random number generatingalgorithm, may be employed.

If it is, and time-of-next transmission scheduling is employed, theprocessor is operative to generate a schedule of random transmissiontimes as shown by a block 120, and then is operative to transmit itsdata packets as shown by a block 122.

As shown by a block 124, the processor is then operative to determine ifthirty (30) seconds have elapsed since the last temperature measurement.If thirty (30) seconds have not elapsed, processing returns to the block114. Although thirty (30) second temperature measurement intervals arepresently preferred, other temperature measurement intervals could beemployed.

As shown by a block 126, if thirty (30) seconds have elapsed, theprocessor is operative to measure the temperature, and processingreturns to the block 114.

Referring now to FIG. 8, generally designated at 130 is a frontelevational view of one embodiment of the multichannel base station ofthe multi-station RF thermometer and alarm system of the presentinvention. The multichannel base station 130 includes a housing 132, aneasy-to-read multi-field reconfigurable display 134 mounted to thehousing 132, a scroll key 136, a control panel schematically illustratedby bracket designated 138 and a control panel door 140 that protects thecontrol panel 138 when it is not being used. The base station 130includes one (1), two (2) position channel switch, a piezo audiblealerter and an audible alerter disable switch, not shown. Although achannel setting DIP switch is presently preferred, other channel settingmeans in the receiver could be employed.

The control panel 138 includes three (3) alarm keys 142, 144, and 146respectively marked “set min”, “set max”, and “done on/off”; a“low/high” “when?” key 148; a “° C./F.” key 150; an hour set key 152marked “hour”; a minute set key 154 marked “minute”; a “12/24” key 156;a month key 158 marked “month”; a day key 160 marked “day” and a yearkey 162 marked “year”.

The multichannel base station 130 is operable in three (3) basic modes.In a decode/display mode described more fully hereinbelow, themultichannel base station 130 concurrently displays temperatureinformation for each active location (remote and base), as well asdisplays temperature high and low information for any location selectedby depressing the scroll key 136.

In alarm set mode described more fully hereinbelow, the multichannelbase station 130 allows the user to independently set alarm minimum andmaximum temperature limits for each temperature location by use of thescroll key 136 and the set min, set max, and on/off keys 142, 144, 146.

In alarm announce mode described more fully hereinbelow, themultichannel base station 130 provides audible, visible and/or remotesignal indications whenever one or more monitored locations havetemperature values that are out-of-bounds.

The C/F key 150 changes the display from centigrade to Fahrenheit in anymode.

The low/high when? key 148, when depressed, displays the high and lowtemperatures for locations selected by the scroll key 136, as well asthe time when those highs and lows were registered.

The hour, minute and 12/24 keys 152, 154, and 156 set the time; and themonth, day, and year keys 158, 160, and 162 set the date.

Description labels, not shown, may be provided on the inside of the door140 to identify the locations of each of the one or more remote RFthermometers.

Referring now to FIG. 9, generally designated at 190 is a functionalblock diagram of the multichannel base station of the multi-station RFthermometer and alarm system of the present invention.

A digital controller 192, preferably a Samsung KS57C2616 microcontrollerwith internal ROM and RAM, is connected to a local temperature sensor194 (preferably consisting of a OKI Semiconductor MSM64162microcontroller and Semitec 103AT-2B thermistor), a receiver 196, amulti-field re-configurable display 198, control panel 200, channel setswitches 202 and to visible and audible alarms respectively designated204, 206.

The local temperature sensor 194 preferably includes a thermistorlocated in the base station operative to sense the temperature in theenviron thereof. Preferably, the local temperature sensor 194 includes amicrocontroller, not shown, which measures the local temperature andsends this to the digital controller 192 which processes and displaysthe data on the display 198 in a manner to be described.

In one preferred embodiment, the digital controller 192 processes datareceived by the receiver 196 and displays data on the display 198 fromup to four (4) remote temperature sensors, although a different numberof remote temperature sensors could be employed. The controller 192 alsomonitors the keypad 200, keeps track of the time and date, and checksfor alarm conditions (temperature exceeding user-specified limits at anylocation). In one embodiment, power is supplied by an external voltageadapter, and the multi-station base station is always “on.” In anotherembodiment, where time-to-next-transmission data is provided, themulti-station base station is battery powered, waking-up to receivetransmissions at scheduled times out of “sleep” mode. A battery backupcircuit maintains the clock and user settings in event of power failureor power down. The visible alarm 204, preferably an LED, and the audiblealarm 206, preferably a piezoelectric beeper, indicate the presence ofan alarm condition.

Referring now to FIG. 10, generally designated at 220 is a schematiccircuit diagram of the receiver 196 (FIG. 9) of the multichannel basestation of the multi-station RF thermometer and alarm system of thepresent invention. The receiver 220 includes a tuned circuit illustratedby dashed box 222 that improves selectivity. Capacitors C11, C13, C15and inductors L2, L3 preferably are tuned to three hundred and fifteen(315) megahertz.

An input buffer schematically illustrated by dashed box 224 thatminimizes radiation from the antenna is connected to tuned circuit 222.Buffer 224 includes transistor amplifier Q3. Capacitors C12, C14 couplethe input signal to the base of transistor Q3, while resistors R6, R10and R14 bias transistor Q3 to operate in a linear manner. R6 also servesas a collector load resistance. Capacitor C4 is a power supplydecoupling capacitor.

A demodulator schematically illustrated by dashed box 226 for detectingthe received signal is connected to transistor Q3 of the input buffer222 via coupling capacitor C8. The demodulator includes transistor Q2operated as a super-regenerative detector. Resistors R3, R4, R13 and R18define the operating point of transistor Q2. Capacitors C7, C15 andresistors R4, R18 form the quench network for the super-regenerativedetector. Inductor L4 serves to isolate the signal voltage from thebiasing network. Resistor R15 and capacitor C19 provide a low-passfilter to remove quench-frequency components from the detector output,while the filtered output is coupled to the data slicer input viacapacitor C17. Capacitor C1 provides power supply decoupling. InductorL1 in conjunction with capacitors C5 and C10 form a tank circuit tunedto resonate at three hundred and fifteen (315) megahertz.

Data slicer schematically illustrated by dashed box 228 for extractingdigital data from the detected signal is connected to the detector 226.The data slicer looks at the detector output, and responds to variationsabout the average signal level, corresponding to the digital datastream. Operational amplifier marked “U2A” is configured as anon-inverting amplifier to boost the detected signal. Operationalamplifier marked “U2B” is configured as a comparator with hysteresis(Schmitt trigger circuit). Resistors R1 and R8 and capacitor C17 couplethe demodulated signal to U2A while providing a high-pass filter toremove DC and slowly varying AC components. Resistors R5 and R9 set thegain of U2A. Resistors R1 and R2 provide a reference voltage to thenon-inverting input of U2A. Capacitor C18 provides power supplydecoupling. Capacitor C9 and resistor R11 low-pass filter the signalgoing to the inverting input of U2B. Resistors R16 and R17 set theamount of hysteresis. Resistor R16 also couples the U2A output to theU2B non-inverting input.

A level translator schematically illustrated by dashed box 230 isconnected to the data slicer 228. With the RF carrier ON, the dataoutput is approximately 0.2 volts; with the RF carrier OFF, the dataoutput is positive five (+5) volts. Transistor Q1 is a clippingamplifier. Resistor R12 couples the data slicer output to the base ofQ1. Resistor R7 is the collector resistor. Capacitor C20 prevents RFenergy from the digital board from being fed back to the receiverthrough the data output. Capacitor C6 is a power supply bypasscapacitor.

Referring now to FIG. 11, generally designated at 240 is a state diagramof the controller 192 (FIG. 9) of the multichannel base station of themulti-station RF thermometer and alarm system of the present invention.As shown by a block 242, the processor is operative in adecode/temperature display mode; as shown by a block 244, is operativein an alarm set mode; and as shown by a block 246 is operative in analarm announce mode. As shown by an arrow marked “min, max, done”extending between the decode/temperature display mode 242 and the alarmset mode 244, the processor transitions from mode 242 to mode 244whenever the user presses the min, the max, or the done key 142, 144, or146 (FIG. 8).

As shown by an arrow marked “on/off, 20 sec's” extending between alarmset mode 244 and decode/temperature display mode 242, the processor isoperative to transition from the alarm set mode back to thedecode/temperature display mode whenever the operator depresses the doneon/off key 146 (FIG. 8), or when twenty (20) seconds of inactivity haveelapsed.

Whenever an out-of-bounds alarm condition exists at any of the remoteand/or base locations, the processor is operative to transition from thetemperature display mode 242 to the alarm announce mode 246 asillustrated by an arrow 252 marked “alarm condition.”

As illustrated by an arrow marked “on/off” extending from the alarmannounce mode 246 the decode/temperature display mode 242, the processoris operative to transition from the alarm display mode to thedecode/temperature display mode whenever the operator pushes the done,on/off key 146 (FIG. 8).

As illustrated by an arrow marked “min, max” extending between the alarmannounce mode 246 and the alarm set mode 244, the processor is operativeto transition from the alarm announce mode to the alarm set modewhenever the operator depresses the min key 142, or the max key 144(FIG. 8).

With reference now to FIG. 12, which shows a pictorial diagram generallydesignated 270 that illustrates the display of the multi-fieldre-configurable display configured in decode/display mode, the operationof the multi-channel base station in decode/display mode will now bedescribed. In decode/display mode, the display includes acomparatively-large active location field 270 and five (5)comparatively-smaller temperature station (remote and base) fieldsgenerally designated 272. Each of the five (5) temperature stationfields 272 includes a temperature field 274, an alarm set field 276, anda station ID field 278.

A daily low icon field 280, a daily low temperature field 282, a dailyhigh icon field 284, and a daily high temperature field 286 are providedbelow the active location field 270. Degree centigrade and degreeFahrenheit fields 288, 290 are provided immediately to the right of theactive location field 270.

Time field 292, and a date field 294, are provided adjacent the bottomof the display.

Upon startup, the initial display is called the “idle” display whichshows all temperatures for all active locations (base and remote) in thefive (5) temperature station fields 272, and displays the base stationtemperature in the active location field 270. Each location is numbered“1”, “2”, “3”, “4”, and “base” in the station identification fields 278.Only locations that have active data are displayed. All other locationsremain blank, including their location number. All alarms are initiallyoff. Default is degrees Fahrenheit.

A circle, not shown, around the location number is displayed in thestation identification field 276 to indicate the active location.

The lowest and highest registered temperature in the past twenty four(24) hours (preferably reset at midnight each day) is displayed in thelow and high temperature fields 282, 286 below the active large readouttemperature field 270, and high and low icons are displayed in the lowand high icon fields 280, 284. The temperature display for all locationsis ° F./° C. switchable by depressing the ° C./F. key 150 (FIG. 8), andthe corresponding icon is displayed in the centigrade and Fahrenheiticon fields 288, 290.

If a good signal has not been received from a remote transmitter in afifteen (15) minute period, a bad signal screen indicator (preferably,“Blank”) is displayed in that temperature location field 274. If thefaulty location is the active location, then both the large displayreadout 270 and the smaller temperature display 272 are blanked.

For the eleven (11) keys of the control panel 138 (FIG. 8) accessed byopening the door 140 (FIG. 8) on the front of the unit, pressing a keyonce gets you into its function and pressing it again takes you back outof the function to idle screen. The exception is for “set min” and “setmax” keys 142, 144 (FIG. 8); the “alarm on/off/done” key 146 (FIG. 8)needs pressed to exit.

When in a set up mode (time, date, alarm), if no keys are pressed fortwenty (20) seconds, then the display returns to the idle display andany changes made by the operator inside any function are saved. Theexception is exiting in “alarm announce” mode, either by pressing thedone/on/off key 146 (FIG. 8) or by pressing the min or max keys 142, 144(FIG. 8).

The “C/F” key 150 and the “12/24” key 156 (FIG. 8) alternate betweentheir two modes each time the key is pressed.

From idle display, the “low/high/when?” button 148 (FIG. 8) when pressedflashes the daily low icon in the daily low icon field 280 while itshows the active location temperature and the hours/minutes when thisdaily low temperature was recorded. After five (5) seconds, the displayflashes “daily high” for five (5) seconds in the daily high icon field284 and shows temperature and time of day when the daily high wasreached, then returns to idle display.

The sound on/off slide switch, on the side of the unit, not shown,controls the piezoalerter 206 (FIG. 9). In the “off” state all soundsincluding the key click sound is turned off.

Whenever a user presses an incorrect key a negative (5) quick beepssound is heard and no changes are made.

When in time change mode, if the “12/24” key 156 (FIG. 8) is pressed,then it toggles and leaves time change mode, saves any changes made, andreturns to the idle screen.

When in any set mode, if the receiver receives data from a transmitterit saves it and updates the display only after the operator exits fromthe set mode.

With reference now to FIG. 13, which shows a pictorial diagram generallydesignated 300 of the multi-field re-configurable display configured in“alarm set” mode, the operation of the processor in alarm set mode willnow be described. The set alarms display 300 is generally the same asthe idle display of FIG. 12, except that the daily high and low icon andtemperature fields are reconfigured to display minimum and maximum icons302, 304 and minimum and maximum value fields 306, 308; and except thata “set temperature” icon field 310 is provided.

When a user presses the “set min” or “set max” buttons 142, 144 (FIG.8), the display changes from the idle display to the “set alarms”display. In the set alarms display, the active location is the onlytemperature shown (in the lower temperature area 272 and in the largerupper display area 270). The daily high/low values disappear, and arereplaced by the min and max alarm range temperature values in the minand max value fields 306, 308. When the current temperature locationgoes outside these values, then the alarm mode to be described for thislocation becomes active.

Alarm min/max values are set one location at a time. The first time the“set min” or “set max” buttons 142, 144 (FIG. 8) are pressed, the “min”number shows five (5) degrees below the current temperature of thatlocation and the “max” value starts at five (5) degrees above thecurrent temperature in the min and max value fields 306, 308. Afterthis, when entering new set min and set max values, the values will bethe previously set values.

To set the minimum and maximum temperature targets for a location, thescroll bar 136 (FIG. 8) is depressed to select the location to set. Inthe set alarms display mode, the active location is the only temperatureshown in the temperature station fields 272 and in the active locationfield 270.

The set min key 142 (FIG. 8) is depressed once. The words “set min”start flashing in the minimum field 302 and “set temperature alarm” isdisplayed in the set temperature icon field 310.

The scroll bar 136 (FIG. 8) is then depressed to adjust the temperaturelimit up or down until the desired number is reached. Adjustment occursone-tenth (0.1) degrees at a time at a rate of two (2.0) degrees persecond. When in alarm min/max set mode, the scroll rate goes to five (5)degrees/second if the scroll key 136 (FIG. 8) is held for more thanthree (3) seconds.

In a similar manner, the set max key 144 is depressed and the scroll bar136 (FIG. 8) is then depressed to adjust the maximum temperature aswell, whereupon the set max words start flashing in the max icon field304.

To exit alarm set mode, the done key 146 (FIG. 8) is depressed. Thealarm mode is automatically switched to “on” upon exit. An icon appearsin the alarm set field 276 beside the location number in the stationidentification field 278 to indicate that this location is now in the“on” state. At the top the display, the daily low and high temperaturesbeing displayed for that location are replaced with the min and max settemperatures for that location while the alarm is in the “on” condition.

When in the alarm set mode the minimum temperature cannot go above themaximum temperature and the maximum temperature cannot go below theminimum. A beep is heard if min and max become equal.

With reference now to FIG. 14, which shows a pictorial diagram generallydesignated 330 of the multi-field re-configurable display configured inalarm announce mode, the operation of the processor in alarm announcemode will now be described. The alarm announce mode display 330 isgenerally the same as the alarm set display 300 (FIG. 13), except thatthe set temperature icon field is reconfigured as a temperature alarmicon field 332, and an LED alarm 334 and an audible alarm, not shown,are enabled.

If the temperature of any location goes outside the min-max alarm rangeand the alarm for that location has been turned on (icon displayed inthe alarm set field 276 beside the location identifier in the stationidentification field 278), then an alarm announce state exists and thedisplay goes into the “alarm announce” display mode. The location withthe alarm becomes the active location and is the only location thatshows on the display (in the lower 272 and upper 270 display areas). The“temperature alarm” icon is displayed in the temperature alarm iconfield 332, and it flashes. The LED 334 flashes, the “alarm on” icon inthe temperature alarm icon field 332 flashes, and if sound is “on”, thesound beeps.

To exit the alarm announce state, the operator can do several things.(All keys except min, max, and done are locked out and cannot be used).The operator can press the alarm on/off button 146 (FIG. 8) which turnsthe alarm on/off icon off and, after one (1) seconds, the displayreturns to idle mode display. The operator could also press either the“set min” or “set max” buttons 142, 144 (FIG. 8) and the displayimmediately goes to the “set alarms” display mode and the operator mayadjust the min-max range to turn off the alarm in the manner describedabove. If the operator leaves the “set alarm” mode and an alarmcondition still exists, then the display returns to the idle display forone (1) second, then returns to the “alarm announce” display.

When a multiple alarm condition exists, then the “alarm announce”display shows all locations in the temperature station fields 272 thathave an alarm condition. The “active” location is the location with thelowest number (e.g., “1” instead of “3”, or “2” instead of “3”, etc.;“base” location is location “0”). The operator depresses the scroll key136 (FIG. 8) to handle each alarm state, one location at a time, in themanner described above. When an alarm is cleared, then after one (1)second, that location disappears from the display and the next lowestnumber location become the “active” location. When the last location iscleared, then the display waits two (2) seconds and returns to idledisplay.

If a good signal has not been received from a remote transmitter in afifteen (15) minute period, that temperature location goes blank,indicating a bad transmission. If the faulty location is the activelocation, then both the large display read out and the smallertemperature display with the location number defaults to the base as theactive location.

Referring now to FIG. 15, generally designated at 350 is a flow chart ofthe processor of the multi-channel base station of the multi-station RFthermometer and alarm system of the present invention. As shown by ablock 352, the processor is operative to determine if any temperaturedata is available. In one embodiment, the processor is always on,monitoring for temperature data. In another, it is “asleep,” waking upat scheduled times to monitor for temperature data. Any suitable datamonitoring technique, such as an interrupt, may be employed.

If data is available, the processor is operative to determine whethertwo (2) frames of the redundantly transmitted data match as shown by ablock 354.

As shown by a block 356, if two (2) frames match, the processor isoperative to update the system data. System data includes the time oflast receipt and the minimum and maximum received temperature valuesreceived in a twenty four hour period.

As shown by a block 358, the processor is then operative to determinewhether the received temperature data is out of bounds.

If it is, as shown by a block 360, the processor is operative to updatethe display, and to transition to alarm mode as shown by a block 362.

If no temperature data is available, or if two (2) frames of theredundantly transmitted data do not match for a given channel, or ifthere is no out of bounds conditions, the processor is operative todetermine whether there has been a key press as shown by a block 364.

If there was a key press on the control panel, the processor isoperative to handle the key press as shown by a block 366 and to updatesystem data as appropriate.

As shown by a block 368, if the keypress input changed operating mode,the processor is operative to transition to alarm set mode as shown by ablock 368.

As shown by a block 370, the processor is then operative to determinewhether any data is older than fifteen (15) minutes since the lasttemperature data was received.

If it is, the processor is operative to blank the record as shown by ablock 372.

As shown by a block 374, the processor is then operative to update thedisplay, and processing returns to the block 352.

Referring now to FIG. 16, generally designated at 400 is an elevationalview of the front of another embodiment of the RF weather station of themulti-station RF thermometer and alarm system of the present invention.The RF weather station 400 includes a water-resistant housing 402, afirst weather parameter sensing probe connected to the housing 402 viaan elongated flexible waterproof cable that senses temperature, notshown, a second weather parameter sensing probe within housing 402 thatsenses percent relative humidity, not shown, and a display 404. Like theembodiment described above in connection with the description of FIGS. 2and 3, a chamber, not shown, is provided in the housing 402 in which thecable of the temperature probe may be stowed and payed-out to allow theprobe to reach intended temperature measurement locations as determinedby the needs of each particular applications environment. A weatherstation location identification switch, preferably a sequential selectswitch, not shown, is mounted to the housing 402 to allow user selectionof weather station location number, and a Centigrade/Fahrenheit switch,not shown, is mounted to the housing 402 to allow user selection oftemperature scales. The display 404 displays the temperature sensed bythe selectably extendable first probe mounted to the housing, anddisplays indicia representative of the selected weather station locationnumber, and of the temperature scale selected. The display 404 alsodisplays indicia representative that a data packet to be described isbeing telemetered. The RF weather station 400 is battery-powered, isoperational from minus forty (40) degrees Fahrenheit to one hundredtwenty-two (122) degrees Fahrenheit, and has a range of up to about twohundred fifty (250) feet.

Referring now to FIG. 17, generally designated at 420 is a functionalblock diagram of the portable, battery-powered RF weather station of themulti-station RF thermometer and alarm system of the present invention.Digital controller 422, operatively connected to RAM memory 424 and ROMmemory 426, is connected to sequential-select station identifying switch428 (and Centigrade/Fahrenheit scale select switch), temperature sensor430, humidity sensor 432, LCD display 434, and to the three hundredfifteen (315) MHZ oscillator 436 described above in connection with thedescription of FIGS. 4 and 6, not separately described again for thesake of brevity of explication. In use, each RF weather station is setto a different station identification number by the sequential-selectstation identifying switch 428. The ROM 426 includes plural uniquetransmission schedules to be described, another one of which is selectedfor each setting of the sequential-select station identification switch428. For the three (3) station identification switch settings of thepreferred embodiment, another one of three (3) unique transmissionschedules, preferably {60 seconds+/−1 second}, {60 seconds+/−5 seconds},and {60 seconds+/−10 seconds}, is selected. For example, location “3”will transmit repetitively alternately at fifty (50) seconds and seventy(70) seconds. Although two-phase repeat schedules are presentlypreferred, more than two (2) phase schedules, one-time phase offsets atthe time of start-up to promote substantially contention-free reception,or other unique schedules to substantially preclude contention-inducedinterference at the receiver and to allow the receiver to enterlow-power mode until the time of next transmission, could be employedwithout departing from the inventive concepts.

The controller 422 preferably is the OKI Semiconductor MSM64162. Thetemperature sensor 430 preferably is the Semitec 103AT-2B thermistor.The humidity sensor preferably is the Shinyei Kaisha C5-M3 humiditysensor. The LCD display 434 preferably is a custom-manufactured display.

The controller 422 (1) measures the resistance of the thermistor of thetemperature sensor 430 and numerically calculates the temperaturecorresponding thereto, (2) measures the resistance of the humiditysensor 432 and calculates the humidity corresponding thereto, (3)encodes a data packet having first data representative of data type,weather station ID and phase of the two-phase transmission schedule, andredundant second data representative of weather parameter sensed, and(4) controls the RF oscillator 436 to transmit the data frame having theencoded data packets at preselected times. In the preferred embodiment,the controller 422 alternatively transmits temperature data and humiditydata in sequential data packets, although any other method may beselected for telemetry of multiple weather parameter data. Thecontroller 422 performs the functions of displaying the temperature onthe liquid crystal display 434 and the indicia representative of stationidentification, active transmission, temperature scale selected, as wellas checks the battery voltage.

In the preferred embodiment, the controller 422 transmits in accord withthe particular unique transmission schedule selected approximately onceper minute. The average duty cycle of any transmission does not exceedtwenty-five (25) percent, permitting a twelve (12) dB increase in thepeak output power from the transmitter. The transmission consists of apreamble, a sync word, and a setup word followed by two identical dataframes, as shown in FIG. 18.

A modified Manchester-like encoding technique that maximizes receiversensitivity and provides higher output peak power than the embodiment ofFIGS. 2-7 is preferably used for the entire transmission, where a “1” isrepresented by the pulse sequence “1000” and a “0” is represented by thepulse sequence “0100.” The “1” in each pulse sequence indicates thetransmitter is pulsed on for four and one-half (4.5) milliseconds, whilethe “0” indicates that the transmitter is turned off for four andone-half (4.5) milliseconds. This coding technique in accord with thepresent invention provides the twenty-five (25) percent duty cycle, andits accompanying improvement in higher output peak power, and alsoinsures that the transmitter cannot be on for more than one (1)consecutive four and one-half (4.5) millisecond interval, which helps tomaximize receiver sensitivity by minimizing “ripple” in the data slicercircuit.

For example, if a digital “7” is to be sent, which is “0111” in standardBCD representation, it first is transformed in accord with the modifiedManchester encoding technique of the present invention, and transmittedas “0100 1000 1000 1000.” It takes sixteen (16) pulses instead of four(4) bits as a bit is represented by four (4) pulses. Since there areonly four (4) high pulses (1's) and twelve (12) low pulses (0's), theaverage energy output is twenty-five (25) percent “on” and seventy-five(75) percent “off.” When data is joined, two “1's” are never presentside-by-side as a zero (0) is always at least at one end. This maximizesreceiver sensitivity. High pulses butted together become a singledouble-duration pulse, which has the undesirable effect of increasingvoltage ripple in the data slicer, thus degrading its sensitivity. Thisundesirable effect is overcome by the encoding technique of the presentinvention, which makes the data look as much as possible like acontinuous stream of “1000 1000 1000 1000 1000 . . . . ”

The preamble is a string of “1000 1000 1000 . . . ” followed by the syncpulse which is two (2) high periods in length. The redundantly encodedweather data immediately follows.

Example of Complete Transmission:

DATA STREAM: PREAMBLE SYNC SETUP DATA FRAME1 (fixed pattern) (widepulse) (xxx) (yyyy) humidity/temp. phase battery low DATA FRAME2 (zzzz)example: 1000100010001 00011000 100001001000 PREAMBLE SYNC encoded “101” SETUP DATA0100010001000100/0100100010000100/0100100001001000/000010010001000 DATAFRAME 1 encoded “0000” “0110” “0101” “0011”  0  6  5  3 (encoded 65.3 C.temperature)0100010001000100/0100100010000100/0100100001001000/000010010001000 DATAFRAME2Data frame2 is identical to data frame1.

Referring now to FIG. 19, generally designated at 440 is a flow chartillustrating the operation of the controller of the portable,battery-powered RF weather station of the multi-station RF thermometerand alarm system of the present invention.

A shown by block 442, the processor is operative to initialize and todetermine the number and kind of weather parameter sensors and thestation identification number.

A shown by block 444, the processor is operative to measure the value ofthe active sensors. In the preferred embodiment, where temperature andhumidity sensors are present, the processor is alternatively operativeto measure temperature and humidity preferably every five (5) seconds.

As shown by block 446, the processor is operative to convert measuredsensor data to a corresponding temperature and/or humidity weatherparameter. Preferably, the processor of the transmitter of eachbattery-powered weather station computes the relevant weather parameter,thereby off-loading that task away from the processor of the receiver,although unconverted sensor data could be transmitted.

As shown by block 448, the processor is operative to display the currenttemperature data and the location identification number.

As shown by block 450, the processor is then operative to determine thetime-to-next transmission and waits until that time as shown by block452.

As shown by block 454, the processor then transmits the encoded datapacket at the prescheduled time, and processing returns to block 444.

Referring now to FIG. 20A, generally designated at 460 is a frontelevational view of another embodiment of the multichannel base stationof the multi-station RF thermometer and alarm system of the presentinvention. The multichannel base station 460 includes a housing 462, aneasy-to-read multi-field re-configurable display 464 mounted to housing462, a scroll-up and scroll-down key 466, a daily high/low andtemperature alarm setting key 468, and a reset/heat index key 470. Thedisplay 464 includes a comparatively-large, upper portion and acomparatively-smaller, lower portion. The enlarged display portion showsthe temperature of a selected active location, (or selectably its heatindex if that location monitors both temperature and humidity), and thesmaller display portion simultaneously shows for each of the remoteweather stations and the base station as identified by the illustrated“1,” “2,” “3,” and “base” indicia the current temperatures (or percentrelative humidity, for location(s) that monitor both temperature andhumidity, as indicated by the icon “%” for location “2” in FIGS. 20A,B). An indication as shown by the “triangle” icon above location “2” isprovided as to which location is currently selected for display in theupper portion. Depression of the scroll key 466 selects an activelocation for display in the upper portion of the display 464, as shownin FIG. 20B, and depression of the daily high/low and alarm setting key468 displays daily low, daily high, alarm min, and alarm max for anyselected active location in the lower portion of the display 464, asshown in FIG. 20C. Depression of the reset/heat index key 470 displaysthe numeric value of the heat index in the upper portion of the display464 for a selected active location and the indicia “heat index,” notshown, and depression of the reset/heat index key 470 followingdepression of the daily high/low and alarm setting key 468 resets theperiod during which the daily high and daily low values are recorded. Atemperature alarm “on” indicator illustrated by a “bell” icon in theupper left corner of the display 464 indicates temperature alarm “armed”status. Below that, a radio transmission indicator illustrated by icon“(.)” and a temperature trend indicator illustrated by the upwardlydirected “arrow” in the upper portion of the display 464 respectivelyindicate when telemetry is being received and the direction and speed oftemperature change of any active location selected. A flashing “bell”icon is shown in the lower portion of the display 464 for any activelocation that has an out-of-bounds alarm condition. A low batteryindicator and a temperature alarm LED, both not shown, respectivelyprovide an indication of low battery power and a visible indication ofan out-of-bounds alarm condition. A piezoalerter, not shown, provides anaudible indication of an out-of-bounds alarm condition. A temperaturescale selector switch, an alarm on/off key, and a sync key, all notshown, are respectively provided to select temperature scale, turn alarmmode on/off, and initiate sync mode whenever, for example, new remoteweather stations are added or it is otherwise desirable to(re)acquireremote weather station's telemetry. Opposite the “bell” icon, indicia,such as the illustrated “F,” shows the temperature scale selected.

Referring now to FIG. 21, generally designated at 480 is a functionalblock diagram of the multichannel base station of the multi-station RFthermometer and alarm system of the present invention.

A digital controller 482, preferably a Samsung KS57C2308/16microcontroller with internal ROM and RAM, is connected to a localtemperature sensor 484 (preferably consisting of the OKI SemiconductorMSM64162 microcontroller and the Semitec 103 AT-2B thermistor), thereceiver 486 (described above in connection with the description of FIG.10, not separately described again for the sake of brevity ofexplication), multi-field re-configurable display 488, keypad 490, andto visible and audible alarms respectively designated 492, 494. Thecontroller 482 is battery-powered, and turns the receiver 486 “on” and“off” at times scheduled to receive transmissions from active locationsas determined by reception clocks 496. For the presently preferredembodiment that monitors telemetry from three (3) remote weatherstations of the type described above in connection with the descriptionof FIGS. 16-19, three (3) reception clocks are maintained, but adifferent number could be employed in accord with the present invention.

Referring now to FIG. 22, generally designated at 500 is a state diagramof the controller 482 (FIG. 21) of the multichannel base station of themulti-station RF thermometer and alarm system of the present invention.As shown by a block 502, the processor is operative in a decode/displaymode; and as shown by a block 504, is operative in an alarm set mode.

In decode/display mode, the controller is operative to identify whichremote locations are active and to set the reception clocks 496 (FIG.21) for each location identified as active. Once active locations areacquired, the controller powers-down the receiver 486 (FIG. 21) exceptat times when transmissions are scheduled, which conserves battery powerand provides long-life operation. When transmissions are scheduled, thecontroller powers-up the receiver 486 (FIG. 21), decodes received datapackets, and updates the display when received telemetry is in properformat and the redundantly transmitted data frames match. It powers-downthe receiver thereafter, or if there is no data frame match, or if thedata format is improper. It lowers its clock speed when it powers-downthe receiver, also to conserve battery power and improve useful batterylife; vice versa, it raises its clock speed when transmissions areexpected. The controller in decode/display mode handles key presses;monitors and displays temperature trends; maintains a record, andselectably displays, the daily high and low values for active locations;monitors and displays out-of-bounds alarm conditions; selectablydisplays the heat index; as well as provides the other audible andvisible indicators described above in connection with the description ofFIG. 20.

When a temperature alarm sounds in decode/display mode, there are two(2) ways to turn the alarm “off.” Either the alarm on/off button isdepressed to turn the alarm function “off” for all active locations, orthe active alarm location is selected and the daily temperature/alarmset button is depressed to reset the alarm bounds in alarm set mode tobe described.

Whenever the heat index key is depressed in decode/display mode, thecontroller is operative to calculate and display heat index for theactive location selected. Heat index is a more accurate measurement ofcomfort than temperature alone, i.e., it provides “apparenttemperature,” what the temperature really feels like. It not only is auseful comfort indicator, but it may prove invaluable in times whentemperature and humidity can lead to dangerous heatstroke levels. Forexample, with a temperature of one hundred (100) degrees Fahrenheit anda relative humidity of sixty (60) percent, the temperature will actuallyfeel like one hundred thirty (130) degrees Fahrenheit. Preferably, thefollowing algorithm is used to calculate heat index.HI=−42.379+(2.04901523*T)−(0.22475541*T*H)−(0.00683783*T*T)−(0.05481717*H*H)+(0.00122874*T*H)+(0.00085282*T*H*H)−(0.00000199*T*T*H*H),where “HI” is heat index, “T” is temperature in degrees Fahrenheit and“H” is percent relative humidity.

Although heat index could be calculated for each combination of humidityand temperature, it is preferred that a look-up data table, not shown,be employed for this purpose.

As shown by an arrow marked “alarm ‘on/off’” extending between thedecode/display mode 502 and the alarm set mode 504, the processortransitions from mode 502 to mode 504 whenever the user presses thealarm “on/off” key. To set or reset temperature alarm limits in alarmset mode upon depression of the alarm on/off button, the scroll key isdepressed to select an active location for which alarm limits are to beset. The daily temperature/alarm set button is depressed to displaydaily high/daily low temperatures and temperature alarm lower and upperlimits in the lower portion of the display 464 (FIG. 20); the alarm minicon will flash showing it is in “set” mode. The scroll keys aredepressed to adjust the lower temperature alarm limit. After that hasbeen set, depression again of the daily temperature/alarm set buttonaccepts the lower range limit, and the alarm max field icon will thenstart flashing. The scroll keys are again depressed to adjust the uppertemperature limit. Depression of the daily temperature/alarm set buttonaccepts that value, and as shown by the arrow extending from the alarmset mode 504 to the decode/display mode 502, the controller returns tothe decode/display mode 502.

Referring now to FIG. 23, generally designated at 510 is a flowchart ofthe processor of the multi-channel base station of the multi-station RFthermometer and alarm system of the present invention. As shown by block512, the processor is operative to identify active locations, set thereception clocks for each active location identified, and to extractvalid weather data. As shown by block 514, the processor then displaysthe temperature and/or humidity weather data recovered for each activelocation on the display.

A shown by block 516, the processor is next operative to determinewhether a predetermined interval, preferably three (3) minutes, haselapsed. If the time interval expired is less than the predeterminedinterval, processing returns to block 512. After the elapse of thepredetermined interval (or if maximum number of locations have beenfound), the processor powers the receiver down as shown by block 518.Although a three (3) minute sync period to acquire active locations ispresently preferred, other intervals could be employed.

As shown by block 520, the processor is next operative to determine if akey has been depressed. If it has, the processor is operative to handlethe keypress and to update system data as appropriate, as shown by block522. If the key is the sync key, processing branches to block 512, andif the key is the alarm on/off key, processing jumps to alarm set modeas shown by block 524.

Otherwise, the processor as shown by block 526 is operative to determineif the current time is equal to any one (1) of the reception clockstime's. If it is, the processor is operative to power the receiver up(and to raise its clock rate) as shown by block 528 and to determine ifdata is available as shown by block 530. If it is, the processor isoperative to determine whether the redundantly transmitted frames matchas shown by block 534, and updates system data and compensates thereception clocks for drift as shown by block 536. The processor is thenoperative to determine whether the temperature data is out-of-bounds forany active location as shown by block 538 and, if it is, to updatesystem data as shown by block 540 and to power the receiver down (andlower its clock rate) as shown by block 532. But if no data isavailable, or if the redundant frames do not match, or if thetemperature data is not out-of-bounds, the processor is operative topower the receiver down (and lower its clock rate) as shown by the block532.

Otherwise, the processor is operative to determine whether any recordsare older than one (1) hour as shown by block 540. If not, the processorupdates the display as shown by block 544. If they are, the processor isoperative to blank those records as shown by block 542, and then toupdate the display as shown by the block 544. The processor then handlesother functions, not shown, such as the temperature trend function,whereafter processing returns to block 520.

Many modifications of the presently disclosed invention will becomeapparent to those of skill in the art without departing from theinventive concepts. For example, other modulation methods such asfrequency-shift keying or phase-shift keying could be employed.Different data encoding schemes, weather information other thantemperature such as humidity and/or pressure and/or sun shine, anddifferent duty cycles could also be employed.

1. A single-channel RF weather monitoring and display system displayinginformation at one location representative of weather monitored atmultiple, other locations remote from said one location, comprising: aportable, battery-powered and hand-holdable weather station adapted forhome and office use, deployable at each of said remote locations,including a hand-holdable housing; a sensor connected to said housingfor measuring a predetermined parameter representative of the weatherprevailing in the environ of said sensor at the location where saidstation may be deployed; an antenna mounted to said housing; means forsetting station ID; and a processor-controlled transmitter mounted inthe housing and coupled to said sensor, said station ID setting meansand said antenna repetitively operative (1) to compile a data packethaving information representative of station ID and of said weatherparameter sensed by said sensor at said location where said station maybe deployed, (2) to generate a unique schedule of at least onetransmission times in such a way that the unique schedule of at leastone transmission times does not overlap in time with that of otherremote locations where portable, battery-operated and hand-holdableweather stations may be deployed and, in accord therewith, to schedule atime to transmit said data packet, and operative (3) to modulate apredetermined-frequency RF carrier wave to transmit said data packet atsaid scheduled time to enable at said one location contention-freereceipt over said single-channel of data packets transmitted from saidmultiple, remote locations where portable, battery-powered andhand-holdable weather stations may be deployed; and a portable basestation adapted for home and office use, deployable at said onelocation, receiving said data packet and displaying said weatherparameter sensed by each said portable, battery-powered andhand-holdable weather station adapted for home and office use.
 2. Thesingle-channel RF weather monitoring and display system displayinginformation at one location representative of weather monitored atmultiple, other locations remote from said one location of claim 1,wherein said unique schedule is a random schedule.
 3. The single-channelRF weather monitoring and display system displaying information at onelocation representative of weather monitored at multiple, otherlocations remote from said one location of claim 1, wherein said uniqueschedule is a schedule of predetermined times.
 4. The single-channel RFweather monitoring and display system displaying information at onelocation representative of weather monitored at multiple, otherlocations remote from said one location of claim 3, wherein saidpredetermined times are determined as two phase schedules consisting ofalternating transmit times defined by {period+phase} and {period−phase}.5. A battery-powered RF weather monitoring and display system,comprising: a portable, battery-powered and hand-holdable weatherstation adapted for home and office use, deployable at a remote locationto monitor a predetermined weather parameter and transmit the monitoredweather parameter to a remote, battery-powered base weather station fordisplay, including a hand-holdable housing; a sensor connected to saidhousing for measuring said predetermined parameter representative of theweather prevailing in the environ of said sensor at the location wheresaid portable, battery-powered weather station may be deployed; anantenna; means for setting station ID; and a processor-controlledtransmitter mounted in the housing and coupled to said sensor and saidantenna repetitively operative (1) to compile a data packet having firstinformation representative of station ID, second informationrepresentative of said weather parameter sensed by said sensor at saidlocation where said portable, battery-powered and hand-holdable weatherstation may be deployed, and third information that enables the remotebattery-powered base weather station to determine time-of-nexttransmission allowing the same to enter battery-power-conserving modeuntil that time, and operative (2) to transmit said data packet to saidportable, battery-powered base weather station; and a portable,battery-powered base weather station adapted for home and office useoperative in response to receipt of a data packet transmitted by saidportable, battery-powered and hand-holdable remote weather station torecover said first information and display said sensed weatherparameter, and to recover said third information and go into batterypower conserving mode until the time of transmission of the next datapacket expected from said portable, battery-powered and hand-holdableremote weather station.